Added Vulkan stub.

src/renderer_vk.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2011-2015 Branimir Karadzic. All rights reserved.
+ * License: http://www.opensource.org/licenses/BSD-2-Clause
+ */
+
+#include "bgfx_p.h"
+#if BGFX_CONFIG_RENDERER_VULKAN
+#	include "../../vk/src/renderer_vk.cpp"
+#else
+
+namespace bgfx
+{
+	RendererContextI* rendererCreateVK()
+	{
+		return NULL;
+	}
+	void rendererDestroyVK()
+	{
+	}
+} // namespace bgfx
+
+#endif // BGFX_CONFIG_RENDERER_VULKAN